Field of the Invention
The present invention relates to a cleaning device for scraping off and removing toner that has adhered to the surface of a rotating photoreceptor, and an image forming apparatus including the cleaning device.
Description of the Related Art
Examples of known cleaning devices for scraping off and removing residual toner that has adhered to the surface of a photoreceptor provided in an image forming apparatus include a cleaning device utilizing a rubber blade entirely made of a rubber material. In a situation where a cleaning device utilizing this rubber blade is used, a contact pressure of the rubber blade with the photoreceptor needs to be set at a level considerably higher than that of a contact pressure originally needed.
This is because it is necessary to take into account a reduction in the contact pressure over time resulting from permanent deformation of the rubber material forming the rubber blade and from chipping of the rubber blade after a long period of use, variation in thickness of the rubber blade, variation in free length of the rubber blade, and the like.
However, when a higher contact pressure of the rubber blade is set with the photoreceptor as described above, a photoreceptor film formed on the surface of the photoreceptor is subjected to abrasion quickly, resulting in a greatly shortened life of the photoreceptor.
Thus, a cleaning device utilizing a so-called tip blade has been widely used, which is formed by affixing a cleaning member made of a rubber material to the tip of a leaf spring member made of metal. In a situation where a cleaning device utilizing this tip blade is used, the permanent deformation of the rubber material is reduced and dimensional accuracy of the tip blade as a whole is improved, thus allowing a great reduction in the contact pressure of the tip blade with the photoreceptor, to provide for a longer life of the photoreceptor.
Examples of documents disclosing a cleaning device utilizing this tip blade include Japanese Laid-Open Patent Publication Nos. 2008-102322, 2008-122683, 2010-60742 and 2010-60860.
However, using a cleaning device utilizing a tip blade causes the contact pressure with the photoreceptor to vary widely depending on the location in an axial direction of the photoreceptor, as compared to a situation where a cleaning device utilizing a rubber blade is used. This is because, in contrast to a rubber blade, a tip blade includes a leaf spring member made of metal in a portion thereof, and depending on a bonding state between this leaf spring member and a support portion supporting this leaf spring member, the actual free length of the tip blade varies depending on the location in the axial direction of the photoreceptor.
If the tip blade is fixed to the support portion using screws, for example, it is inevitable that the contact pressure of the tip blade with the support portion will be distributed non-uniformly, causing the actual free length of the tip blade to vary depending on the location in the axial direction of the photoreceptor. If the tip blade is fixed to the support portion using an adhesive, it is inevitable that the adhesive layer between the tip blade and the support portion will have a non-uniform thickness, causing the actual free length of the tip blade to vary depending on the location in the axial direction of the photoreceptor.
If the contact pressure with the photoreceptor varies depending on the location in the axial direction of the photoreceptor, abrasion of the photoreceptor film also varies depending on the location over time, resulting in a reduction in quality of a formed image. If this contact pressure variation can be suppressed, the contact pressure of the tip blade with the photoreceptor can be set at a lower level, thus providing for a longer life of the photoreceptor.